A Passive Optical Network (PON) consists of an Optical Line Terminator (OLT), which resides in a Central Office (CO). The optical line terminator services a number of Optical Network Units (ONUs) typically connected in a star arrangement using optical splitters, which reside at a premise of a user. The upstream data on the passive optical network going from the optical network units to the optical line terminator is time-multiplexed between the multiple optical network units. Since each optical network unit may be located at a different distance from the optical line terminator, the amplitude of the upstream signal, seen at the optical line terminator, varies between optical network units. A problem occurs when two optical network units send consecutive bursts of data that are at very different power levels.
Current burst-mode optical receiver technology cannot predict the power level of a forthcoming burst of data seen at the receiver of an optical line terminator. This results in a need for long packet preambles in order to satisfy the optical dynamic range requirements for optical line terminator burst-mode input signals as specified in the International Telecommunications Union (ITU) Gigabit Passive Optical Network (GPON) standard (G.984) and ITU Broadband Passive Optical Network (BPON) standard (G.983). These long preambles effectively waste upstream bandwidth of the passive optical network. No current approach utilizes either the Media Access Control (MAC) to assist the optical receiver or utilizes an amplifier to Direct Current (DC) bias the data line to obtain a solution to different incoming optical power levels. The MAC assisted approach leverages the forward looking view of the MAC in that it has specific knowledge of which ONU is scheduled to arrive upstream next and it can use that information to precondition the receiver. In theory, such a receiver could function with almost no preamble at all. The reset based approach using the DC amplifier circuit is a reactive approach that will always require some amount of preamble to train on. Typical reactive circuit topologies that seek to determine an appropriate sampling threshold after the signal has arrived at the LT receiver will always require some amount of preamble to train on.
The passive optical network media access controller has advanced knowledge of which optical network units will be transmitting in an upstream frame. Therefore what is needed is a circuit that the Passive Optical Network (PON) Media Access Controller (MAC) can utilize to assist the Burst-Mode optical Receiver (BMRX) in the task of quickly adjusting to various input power levels in order to shorten the required amount of preamble needed for training. This shorter preamble will effectively lead to increased upstream bandwidth on the passive optical network. The present invention provides a system, method, and computer readable medium that allows the passive optical network media access controller to assist the burst mode receiver to reduce the time required between upstream cells and upstream preamble length, which increases effective bandwidth of the passive optical network.